Hi Folks...
Going thru some of my old notes here, when I found a list I had compiled of carriers using
both the DC-10 & the L-1011 at one time or another, but not necessarily at the same time.
Since the average Joe on the street would never tell them apart, us Anetters certainly would.
Both aircraft are very similar in appearance, seating, and performance, depending on variant.
Here's the 12 carriers I knew of operating both types at any length of time.

AeroPeru
ATA
Arrow Air
British Airways
Caledonian Air
Delta Air Lines
Eastern Airlines
Hawaiian Air
Iberia
LAM
Pan American
United Airlines

If you folks can think of any other carriers that flew both aircraft, please let me know.
BTW, I purposely left out the MD-11, simply because that bird does not compete with
the Tristar like the DC-10 did.
All replies appreciated & welcome. Regards.

"Beer is living proof that God loves us and wants us to be happy." --Ben Franklin

Actually DL operated both aircraft at the same time twice in its history. The first came when Lockheed and Rolls Royce were experiencing financial difficulties, and as a hedge against the L-1011 being cancelled, DL ordered DC-10s. It sold these to UA and then leased them back to operate while the L-1011s were being delivered. The second period came when DL merged with WA and the DC-10s operated routes out of LAX.

Pan Am and BA both had interesting histories in this regard. Pan Am was a major TriStar customer and then acquired its DC-10s after the 1980 merger with National. Mnay have observed that this duopoly of mid-range trijets cost the airline dearly and was one of the major reasons behind its gradual decline in the 1980s. The arrival of A300s and A310s put paid to the trijets.

As for BA, it too had its TriStars from new while it got its DC-10s after the British Caledonian merger. Both fleets operated together for a few years but unlike Pan Am the TriStars went first as 767s arrived in the fleet. The DC-10s were around until about 1999 when the rising fleet of 777-200s usurped them. Some of the DC-10s went to charter arm Caledonian, which was later taken over by JMC.

They were big Tristar users and IIRC they inherited some DC10s when they took over CP air?

I disagree. AC had retired their last L1011s about 5 years before the merger with CP (which was Canadian Airlines then, not CP Air). And Canadian's DC-10s were retired before the merger so they were never operated by AC.

Quoting Trintocan (Reply 7):Pan Am was a major TriStar customer and then acquired its DC-10s after the 1980 merger with National. Mnay have observed that this duopoly of mid-range trijets cost the airline dearly and was one of the major reasons behind its gradual decline in the 1980s.

I don't think that was the case at all. More like the decision to replace these fleets with older, less efficient and more costly 741's. Which were deployed on routes they weren't suited for and often only half full.